Transient third-order optical nonlinearityχ^(3)of ZnO microcrystallite thin films is measured at various temperatures by using femtosecond degenerate four-wave-mixing.Room-temperature excitonic enhancement of is obse...Transient third-order optical nonlinearityχ^(3)of ZnO microcrystallite thin films is measured at various temperatures by using femtosecond degenerate four-wave-mixing.Room-temperature excitonic enhancement of is observed.The magnitude ofχ^(3)ranges between 10^(-4)to 10^(-6)esu from 4.2K to room temperature.The measuredχ^(3)response time ranging from 200 to 300 fs ultrafast for temperature down to 4.2K.展开更多
We report the femtosecond time-resolved studies of room temperature exciton recombination and ultrafast stimulated emission dynamics in ZnO microcrystallite thin films.A free exciton photoluminescence lifetime of a fe...We report the femtosecond time-resolved studies of room temperature exciton recombination and ultrafast stimulated emission dynamics in ZnO microcrystallite thin films.A free exciton photoluminescence lifetime of a few tens of picoseconds and a decay time of a few picoseconds for the stimulated emission were observed.The relatively slow rise time(3ps)for the P band as the result of exciton-exciton scattering compared with the 0.8ps rise time for the N band attributed to electron-hole plasma recombination clearly distinguished the two stimulated emission processes.展开更多
A femtosecond Kerr-lens mode-locked Cr:LiSGaF laser based on a compact cavity geometry is demonstrated.With a combination of 488,476,and 458nm lines as a pump source,58fs pulses centered at 845nm were generated.The av...A femtosecond Kerr-lens mode-locked Cr:LiSGaF laser based on a compact cavity geometry is demonstrated.With a combination of 488,476,and 458nm lines as a pump source,58fs pulses centered at 845nm were generated.The average output power is 30mW,and time-band product is 0.331,assuming a sech^(2) pulse shape.Neither acousto-modulator nor physical aperture or slit were used in this cavity.展开更多
The N=3 femtosecond solitonlike pulses are observed directly in a self-mode-locked Ti:sapphire laser as well as even higher-order solitonlike pulses for the first time.When the laser is operating in a stable train of ...The N=3 femtosecond solitonlike pulses are observed directly in a self-mode-locked Ti:sapphire laser as well as even higher-order solitonlike pulses for the first time.When the laser is operating in a stable train of mode-locked pulses,the periodic pulse train appears by only varying the intracavity dispersion.The soliton period with N=3 corresponds to a cavity round trip number of 164.展开更多
基金Supported by the National Natural Science Foundation of China under Grants No.69608002the Excellent Young Teacher's Foundation of the Ministry of Education.
文摘Transient third-order optical nonlinearityχ^(3)of ZnO microcrystallite thin films is measured at various temperatures by using femtosecond degenerate four-wave-mixing.Room-temperature excitonic enhancement of is observed.The magnitude ofχ^(3)ranges between 10^(-4)to 10^(-6)esu from 4.2K to room temperature.The measuredχ^(3)response time ranging from 200 to 300 fs ultrafast for temperature down to 4.2K.
基金Supported by the National Natural Science Foundation of China under Grant No.69608002the Excellent Young Teacher's Foundation of the Minis try of Education.
文摘We report the femtosecond time-resolved studies of room temperature exciton recombination and ultrafast stimulated emission dynamics in ZnO microcrystallite thin films.A free exciton photoluminescence lifetime of a few tens of picoseconds and a decay time of a few picoseconds for the stimulated emission were observed.The relatively slow rise time(3ps)for the P band as the result of exciton-exciton scattering compared with the 0.8ps rise time for the N band attributed to electron-hole plasma recombination clearly distinguished the two stimulated emission processes.
基金Supported by the National Natural Science Foundation of China under Grant No.69608002the Excellent Young Teacher's Foundation of the Ministry of Education。
文摘A femtosecond Kerr-lens mode-locked Cr:LiSGaF laser based on a compact cavity geometry is demonstrated.With a combination of 488,476,and 458nm lines as a pump source,58fs pulses centered at 845nm were generated.The average output power is 30mW,and time-band product is 0.331,assuming a sech^(2) pulse shape.Neither acousto-modulator nor physical aperture or slit were used in this cavity.
基金Supported by the Returned Teacher's Foundation of the National Education Committeethe Key Research Project in Climbing Program from the National Science and Technology Commission of Chinathe Hong Kong Research Grant Council Project HKUST 633/945P.
文摘The N=3 femtosecond solitonlike pulses are observed directly in a self-mode-locked Ti:sapphire laser as well as even higher-order solitonlike pulses for the first time.When the laser is operating in a stable train of mode-locked pulses,the periodic pulse train appears by only varying the intracavity dispersion.The soliton period with N=3 corresponds to a cavity round trip number of 164.
